Leaders of the Group of Seven (G7) industrialized nations say they have agreed to do more to fight terrorism and narrowed their differences on trade, but they failed to settle a disagreement with U.S. President Donald Trump on climate change.

A joint statement signed by G7 leaders meeting on May 26 in the resort town of Taormina, Sicily, demanded that Internet providers and social media firms take action against extremist content online.

"The G7 calls for Communication Service Providers and social media companies to substantially increase their efforts to address terrorist content," it said.

The leaders also pkedged a joint effort to track down and prosecute foreign fighters from conflict areas such as Syria.

The move comes four days after a suicide bombing in Manchester killed 22 people. The extremist group Islamic State (IS) claimed responsibility for the attack.

The G7 consists of the United States, Britain, Canada, France, Germany, Italy, and Japan, but EU representatives are also attending.

Climate Policies 'On Hold'

Italian Prime Minister Paolo Gentiloni, host of the two-day summit, said the leaders were narrowing their differences on trade ahead of the release of the official summit declaration.

"We are still working" on the content of the trade declaration, "but it seems to be that today's straight discussions have highlighted common points of views on which we can work," he said.

He said climate policies remain "on hold" as Trump has still not decided whether to fulfill his vow to pull out of the 2015 Paris climate change agreement, which all other G7 members support.

"There is one open question, which is the U.S. position on the Paris climate accords," Gentiloni said. "All others have confirmed their total agreement on the accord."

"We are sure that after an internal reflection, the United States will also want to commit to it," he added.

German Chancellor Angela Merkel told reporters that Trump was urged by all the other leaders to back the Paris accords.

British Prime Minister Theresa May said the G7 leaders made clear that Russia and Iran must push for a cease-fire in the six-year civil war in Syria. Moscow and Tehran support Syrian President Bashar al-Assad, while the United States and Turkey support differing rebel groups.

May also said they agreed to put additional pressure on North Korea to halt its illegal ballistic-missile tests.

U.S. President Donald Trump (left) speaks with the president of the European Council, Donald Tusk, at the G7 summit.

Earlier, President Donald Tusk said the gathering would "no doubt" be "the most challenging G7 summit in years."

Some of the participants hold "very different positions on topics such as climate change and trade," Tusk said before the two-day summit opened on May 26 in the resort town of Taormina.

"Most importantly, unity needs to be maintained when it comes to defending the rules-based international order," he said, warning that "if our group is not determined and united enough, the situation in the world can really get out of hand."

The G7 summit in Taormina is the first such meeting for U.S. President Donald Trump, who took office in January. Trump is expected to face questions from other leaders about his positions on issues such as trade, climate change, and the conflict in Ukraine.

The leaders are also due to discuss security cooperation following the May 22 bombing at a concert in Manchester, England, that killed 22 people and was allegedly carried out by a 22-year-old Briton of Libyan descent.

Tusk said that he "totally agreed" with Trump "when he said the international community, the G7, the United States, Europe should be tough, even brutal, with terrorism" and the Islamic State (IS) extremist group.

Russia Sanctions

Tusk also called on G7 leaders to maintain sanctions on Russia over its aggression in Ukraine.

"Since our last G7 summit in Japan, we haven't seen anything that would justify a change in our sanctions policy towards Russia," Tusk, who coordinates policy for the EU's 28 leaders, told reporters.

"I will appeal to the other G7 leaders to reconfirm this policy," he added.

Since 2014, the EU and the United States have maintained sanctions on Russia over its seizure of Crimea and its actions in eastern Ukraine, where a war between Russia-backed separatists and government forces has killed more than 9,900 people.

Tusk spoke a day after a U.S. official, asked whether Trump plans to extend the U.S. sanctions, indicated that the president had not decided.

"I think the president is looking at it. Right now, we don’t have a position," White House economic adviser Gary Cohn told reporters on Air Force One en route to Sicily for the summit. He added that Trump has "many options."

However, later on May 26 at the G7 summit, Cohn came out strongly in favor of sanctions.

“We are not lowering our sanctions on Russia," he told reporters. "If anything, we would probably look to get tougher on Russia."

The G7 summit kicked off with a ceremony at an ancient Greek amphitheater overlooking the sea, where the leaders stood together for a family photo against the backdrop of the Mediterranean.

"Getting ready to engage G7 leaders on many issues including economic growth, terrorism, and security," Trump tweeted before the summit."

Western news agencies quoted diplomatic sources as saying that Trump and the leaders of Britain, Germany, France, Italy, Japan, and Canada had similar views on many issues, but that Washington remained isolated on commerce and the environment.

Ahead of the summit, European Commission President Jean-Claude Juncker rejected reports that Trump had aggressively condemned German trade policies during a meeting in Brussels on May 25.

German media reports said Trump had denounced Berlin's policies as "very bad" and had signaled that he wanted to limit sales of German cars in the United States.

"He did not say that the Germans were behaving badly," Juncker said in Sicily ahead of the G7.

Juncker called the media reports exaggerated, saying it was "not true" that Trump had been aggressive toward Germany in the talks.

'Fairly Robust Talks'

An unnamed senior Italian diplomat said Trump and the heads of Britain, Germany, France, Italy, Japan, and Canada had similar views on many issues ahead of the two-day summit, but Washington remained isolated on commerce and the environment.

European Union states want a clear U.S. pledge "to fight all forms of protectionism," the diplomat said. But they were struggling to convince the U.S. president of the merits of free trade.

"We will have a very robust discussion on trade and we will be talking about what free and open means," White House economic adviser Gary Cohn told reporters late May 26.

He also predicted "fairly robust" talks on whether Trump should honor a U.S. commitment to cut greenhouse-gas emissions under the 2015 Paris Agreement.

He said the president, who has dismissed global warming as a "hoax," would make a final decision when he returned home, but stressed that he would put economic development first.

European diplomats expect their leaders to put pressure on Trump about the Paris emissions deal, which has comprehensive support across the continent.

After visits to Saudi Arabia, Israel, and the Palestinian Territories, Trump met Pope Francis in Rome on May 24 and held talks May 25 with the heads of the European Union and the NATO military alliance in Brussels.

In a tweet on May 26, Trump said his first trip abroad had been "very successful."

"Just arrived in Italy for the G7. Trip has been very successful. We made and saved the USA many billions of dollars and millions of jobs."